NanoVNA-H4 Hanging on scan

[TK0130]

I recently designed a clone of the nanoVNA-H4 for a research project as I wanted a better (larger) platform to tinker with than the nanoVNA. (Larger components, low frequency stuff and I wanted to just tinker in general.)

Anyway, I can flash firmware to it using DFuse and talk to it over USB (Serial port, 115200 baud rate.) and everything seems to be working there. (uC is booting up OK etc.)

The issue is that it hangs anytime I try to do anything "analog" (Scan, etc.) and thus crashes nanoVNA saver.

I was wondering if you had any advice on where to start debugging.

Attached is the schematic I used as a reference and the firmware file.

NanoVNA.H4.v1.2.20(1).zip

The only major deviations from the attached schematic are that I gutted out the battery circuitry and the LCD as I didn't need them. (I still broke out the connections to pads just in case.) I also used the STM32F303